scripts: bind ~/.ssh over the chroot's ~/.ssh.

This also mounts the path to our ssh-agent socket (usually in /tmp) inside the
chroot so we can use our external agent.

TEST=None

BUG=None

Change-Id: I543e8b2527be9958c1158234f39ecc34fc9dd0df
Signed-Off-By: Elly Jones <ellyjones@chromium.org>
Signed-Off-By: sosa <sosa@chromium.org>

Review URL: http://codereview.chromium.org/3277006

enter_chroot.sh

@@ -31,6 +31,7 @@ DEFINE_boolean official_build $FLAGS_FALSE \
   "Set CHROMEOS_OFFICIAL=1 for release builds."
 DEFINE_boolean mount $FLAGS_FALSE "Only set up mounts."
 DEFINE_boolean unmount $FLAGS_FALSE "Only tear down mounts."
+DEFINE_boolean ssh_agent $FLAGS_TRUE "Import ssh agent."
 
 # More useful help
 FLAGS_HELP="USAGE: $0 [flags] [VAR=value] [-- \"command\"]
@@ -104,6 +105,20 @@ function setup_env {
           die "Could not mount $MOUNTED_PATH"
     fi
 
+    if [ $FLAGS_ssh_agent -eq $FLAGS_TRUE ]; then
+      TARGET_DIR="$(readlink -f "${FLAGS_chroot}/home/${USER}/.ssh")"
+      if [ -n "${SSH_AUTH_SOCK}" \
+        -a -d "${HOME}/.ssh" ]
+      then
+        mkdir -p "${TARGET_DIR}"
+        cp -r "${HOME}/.ssh/known_hosts" "${TARGET_DIR}"
+        ASOCK="$(dirname "${SSH_AUTH_SOCK}")"
+        mkdir -p "${FLAGS_chroot}/${ASOCK}"
+        sudo mount --bind "${ASOCK}" "${FLAGS_chroot}/${ASOCK}" || \
+          die "Count not mount ${ASOCK}"
+      fi
+    fi
+
     MOUNTED_PATH="$(readlink -f "${FLAGS_chroot}/dev/pts")"
     if [ -z "$(mount | grep -F "on $MOUNTED_PATH ")" ]
     then
@@ -274,7 +289,8 @@ fi
 # the source trunk for scripts that may need to print it (e.g.
 # build_image.sh).
 sudo chroot "$FLAGS_chroot" sudo -i -u $USER $CHROOT_PASSTHRU \
-  EXTERNAL_TRUNK_PATH="${FLAGS_trunk}" LANG=C -- "$@"
+  EXTERNAL_TRUNK_PATH="${FLAGS_trunk}" LANG=C SSH_AGENT_PID="${SSH_AGENT_PID}" \
+  SSH_AUTH_SOCK="${SSH_AUTH_SOCK}" -- "$@"
 
 # Remove trap and explicitly unmount
 trap - EXIT